The objective of this research is the elucidation of the normal and abnormal physiology of the recently-discovered, growth-promoting, gastric acid inhibitory polypeptide hormone, human epidermal growth factor (hEGF), which is probably identical to human beta-urogastrone (hUG). Human EGF will be purified from urine in sufficient quantities for use as radioiodinated tracer and reference standard in the current hEGF/UG radioimmunoassay (RIA), for immunizing animals to develop more sensitive RIAs, and for further chemical characterization. High molecular weight hEGF/UG will also be purified from urine and further characterized in terms of its radioreceptor assay (RRA) and RIA activities and its chemical structure. The tissue/cell source(s) of hEGF/UG will be further explored using RIA and RRA of tissue extracts and tissue culture media and immunocytochemistry studies of tissue sections. The effects of estrogens on hEGF/UG secretion and plasma clearance, the levels of plasma hEGF/UG in patients with chronic renal failure, the relationship of hEGF/UG to calcium homeostasis, gastrointestinal and cutaneous integrity, function, repair, and neoplasia will be explored. The ultimate aim is to understand the role of hEGF/UG excess or deficiency in human disease and its therapeutic potential in preventing or curing these diseases.